There are a number of cosmetic compositions available to consumers to improve the aspect of the skin. In particular these cosmetics are used to prevent or to fight against skin ageing signs such as loss of firmness, decrease of skin thickness, fine lines, wrinkles, loss of elasticity, sagging, diminished rate of turnover, and abnormal desquamation. These effects are intensified by years of exposure to UV rays, irritants, allergens, and various environmental toxins. Such cosmetic compositions are generally designated as anti-ageing compositions.
The skin consists of three layers, the epidermis, the dermis and the subcutaneous tissue (hypodermis). The skin's extracellular matrix is a complex network of macromolecules, such as collagen or elastic fibers, glycoproteins, glycosaminoglycans and proteoglycans. It provides a physical framework to assume mechanical strength and participates in cell metabolism regulation.